REPTILES 239 



D. reticiilaria (Latreille). Chicken turtle. Carapace narrow, 

 rather high, and olive or brown in color with a net-work of fine yellow 

 lines, each upper marginal with a yellow bar and each under marginal 

 with a black blotch on a yellow field ; plastron yellow; length of carapace 

 125 mm.; width 80 mm.; neck very long: Atlantic and Gulf coastal plain 

 from central North Carolina to Texas and Oklahoma; southward to 

 central Florida. 



9. Gopherus Rafinesque. Land tortoises. Shell high and dome- 

 like; plastron large and often with a hinged front lobe; feet not webbed: 

 3 species in the United States, all herbivorous and strictly terrestrial; 

 they are allied to the giant land tortoises of the Galapagos Islands, the 

 largest of which has a carapace a meter and a third in length and weighs 

 over 225 kilos. 



Key to the United States Species of Gopherus 



ai In the southern and south-central States G. polyphemus. 



a2 In Texas G. berlandieri. 



as In the extreme southwest G. agassizii. 



G. poly phemus (Daudin). Gopher turtle. Carapace with concen- 

 tric lines on each scale, brownish in color; plastron dull yellow, notched 

 behind, extending beyond the carapace in front; length of carapace 

 280 mm. ; width 200 mm. ; inner surface of fore arm with enlarged scales: 

 south Atlantic and Gulf States; northward to South Carolina and 

 Arkansas; gregarious, living in dry, sandy regions and burrowing in the 

 ground. The burrow runs obliquely in the ground to a depth of 4 or 

 more feet, and is enlarged at the end, where a single pair lives. 



G. agassizii (Cooper). Similar to G. polyphemus; no enlarged 

 scales on the inner surface of the fore arm: southwestern Arizona and 

 southeastern California into Nevada and Utah. 



G. berlandieri (Agassiz). Shell globular, being very broad and 

 high; carapace brown and 150 mm. long, 136 mm. wide and 80 mm. 

 high; plastron yellow: southwest Texas into Mexico. 



Family 4. Trionychidae. — The soft-shell turtles. Large turtles 

 with a flat, circular shell which is covered with a leathery skin and not 

 with horny plates or scales; ossification of the carapace not complete; 

 neck very long; head pointed, ending in a flexible proboscis-like snout; 

 jaws powerful, with fleshy lips; feet webbed; toes 5-5; claws y^^,: about 

 30 species, in both hemispheres, 4 in the United States; savage, active 

 turtles, aquatic and carnivorous, valued for food; eggs spherical. It 

 has been demonstrated that these turtles can remain under water 

 several hours at a time, and that they have true water respiration when 



